Back-lighted display panels



July 13, 1965 J. D. I. LOCKE 3,194,954

BACK-LIGHTED DISPLAY PANELS Filed July 2-, 1962 2 Sheets-Sheet'Z Ilnited States Patent 3,194,954 BACK-LIGHTED DISPLAY PANELS John David Ivor Locke, Warnham, Engiand, assignor to Communications Patents Limited Filed July 2, 1962, Eer. No. 206,84)? Claims priority, application Great Britain, July 6, 1961,

24,424/61; Dec. 29, 1961, 46,715/61 3 Claims. (Cl. 240-10) This invention relates to improved means for providing back lighting of a transparent or translucent panel such as is used in classroom training aids.

The present invention has as an object the provision of an improved back-lighted display panel.

According to the present invention, a baclclighted display panel comprises a translucent screen, at least one cellular grid member including partition walls extending from a front face to a rear face of the grid member and bounding open-ended cells, the grid member being bonded to the rear face of the screen along the forward edges of the partition walls, at least one electric lamp holder disposed in relation to a plurality of the cells, the lamp holder unit including at least two retaining parts, each retaining part being adapted to engage with parts adjacent the screen of two opposite walls of a cell in which a retaining part is disposed, to retain the lamp holder in place in relation to at least two cells in a row of cells of the grid member.

In order that the invention may readily be carried into effect, two embodiments will now be described in detail, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective drawing of a back-lighted dis play panel as seen from a viewpoint to one side of and to the rear of the panel;

FIG. 2 is a sectional side elevation of part only of the panel of FIG. 1;

FIG. 3 is a perspective drawing of a first embodiment of a lamp holder for association with two or more of the cell-like compartments shown in FIG. 1;

FIG. 4 is a sectional view of part only of the panel of FIG. 1 with a second embodiment of a lamp holder inserted in place; and

FIG. 4(a) is a detail perspective view of the square grommet of FIG. 4.

Referring first to FIGS. 1 and 2 of the drawings, a display panel 1 comprises a thin, translucent front screen 3 to the rear face of which is secured a cellular grid 5. This grid 5 is a moulding of synthetic plastic material in this example, and can be formed either of a material which is naturally opaque or of a material which is naturally transparent or translucent and is subsequently painted or coated to render the partition walls 7 opaque.

The cellular grid 5, in the example shown, defines a large number of approximately cubical cells or compart ments 9, the edges being, merely by way of example, two inches long. The grid 5 is secured to the rear face of the front screen 3 by adhesive. The adhesive is applied along the front edges 11 of the partition walls 7 of the grid and to the front edges of the peripheral walls 13 of the grid, and allowed to harden after the grid has been clamped into the position shown in FIG. 1, abutting the rear surface of the screen 3. Alternately, the adhesive may be applied in a manner such that parts only of the edges of the partition and peripheral walls of the grid adhere to the screen, for example those parts in the vicinity of positions where the walls intersect.

The type of adhesive used for securing the grid 5 will depend on the material used for the grid and for thescreen. In the example shown, the screen is made of fibreglass. In some instances, the adhesion of the screen It will be appreciated that, for convenience in manu-.

facture, it may be expedient to mount several grid assemblies, such as the grid 5 described, side-by-side on a single screen 3. It will usually be practical to manufacture a unitary screen 3 of the requisite size, which may be several feet square. The grids, however, may individually not exceed eighteen inches square, if standard moulding equipment is used for their manufacture. When several such individual grids are used in conjunction with a single screen, it may be found desirable to remove some or all of the peripheral walls 13 of the individual grids, so that the total thickness of the partition between adjacent compartments 9 lying in adjacent individual grids, shall be uniform with the thickness of the partition between adjacent compartments of the same individual grid.

The grid 5 has two main functions, firstly to provide a support for electric lamps which provide back lighting of the screen 3, and secondly to localise the light emitted by such lamps to the desired areas of the screen 3. In some instances, it may be sufficient to provide only one lamp in a compartment, but in other instances it may be desirable to provide several lamps providing light of different colours, so that by suitable switching of the lamps the colour of the light illuminating that part of the screen may be changed.

By the use of a unitary construction for the grid 5, it is possible to standardise the construction of such display panels, using for example a square cell construction, and yet readily to combine several such cells where a larger area of the screen 3 is to be evenly illuminated.-

Thus, certain of the partition walls can be broken away without seriously affecting the rigidity of the structure. When the grid 5 is moulded from transparent or translucent material, and the partition wall is subsequently rendered opaque by the application of paint, for example, it will not normally be necessary to break away these partition walls, but merely to omit or to remove the paint or other opaque material.

The electric lamps are mounted in the compartment 9 by lamp holder units, of which one embodiment is shown in FIG. 3 and a second embodiment is shown in FIG. 4 bearing the reference and 50' respectively. In the first example shown, the lamp holder 50 has two similar retaining parts. One retaining part comprises a cou pling piece 51 and springs 51A, 51B, and the other retaining part comprises a coupling piece 52 and springs 52A and 52B.

Each spring has the shape of an inverted letter Y and is formed from a length of spring quality wire. The wire is bent double to provide a clamp to grip the associated coupling piece, and the parts forming the limbs of the letter Y are spread apart at the extremities by an amount sufficient to engage parts of opposite walls of a compartment of the grid 5.

In FIG. 3, the coupling piece 51 is gripped by a doubled portion 53 of the spring 51A. Parts 53A and 53B, at the extremities of the limbs, are bent to lie approximately parallel to the compartment walls.

Each coupling piece has the form of a strip and is made of an insulating material such as resin bonded fabric. Each strip is of a length approximately equal to the distance between the cell walls and is provided with notches at the edges, near to the ends where the doubled portions of the spring grip the strip. The spacing between the notches is such that the springs are retained apart by a distance a little less than the spacing between cell walls, so that the two springs of a retaining part may enter a cell without jamming. I

The coupling pieces 51 and 52 are each provided with a row of four equi-spaced holes through which are threaded four substantially straight lengths of bare wire referenced 54, 54A, 54B and 54C. The holes are of a diameter slightly greater than that of the wires and are positioned so that the wires lie parallel to each other. The material and diameter of the wire and the spacing between the wires is such that an annular rubber grommet 55, carrying a lamp socket 56 throughits centre hole, may be supported between and gripped by two of the wires without the wires being permanently distorted out of shape.

In FIG. 3, the grommet 55, carrying lamp socket 56 is supported between wires 54 and 54A in a first position. Wires 54A and 5413 or wires 54B and 54C may be used to support the lamp in a second or a third position if so desired; When more than one lamp is used to illuminate a compartment it is preferable to make use of two or all three positions.

The wires 54 to 54C enable three separately controlled circuits to be provided. The circuits are fed from a source of electric current, which is not shown, of a voltage to suit a lamp 57 retained in socket -5. The wires 54A, 54B and 54C are connected to one terminal of the source, by way of switching devices not shown, which control the operation of lamps connected to the three circuits and which may be located in one or more of the compartments. The wire 54 is connected to the other terminal of the source and acts as a common return for the three circuits. In the example of FIG. 3, one lamp 57 is associated with the circuit provided by wires 54 and 54A.. The filament of the lamp is supplied with current via insulated flexible leads 58, 58A connected to terminals 59, 59A of the lamp socket .56 and to the wires 54 and 54A.

In use, the lamp holder 50 is fitted with retaining parts in two of the compartments 9. Lamp holders having three or more retaining parts may be used where several compartments in a row are .to be illuminated. The retaining parts may be in adjacent compartments or may be separated by one or more compartments.

A second embodiment of lamp holder unit is shown in FIG. 4 under the general reference 56. bodiments 5t) and 5t), like elements are indicated by the same reference numerals. The differences are of detail only.

In the embodiment 50, the grommet 55, which carries the lamp socket 56, is square as shown in FIG. 4a instead of round as shown in FIG. 3. The square shape provides a better grip on the pair of wires 54, 54A and so on and also prevents the grommet from being turned accidently.

In the em The springs 51B, 52B of the embodiment 5d are pro- 7 vided with a detent 63 which engages the underside of the coupling piece 51 or 52 and prevents downward displacement of the piece; V

In FIG. 4, a second lamp holder unit and lamp 67 is shown behind the lamp 57. The lamp 6'7 is of different colour from lamp 57 and'is supplied from wires 54B and 54C. In general, the circuits supplying the two lamps 57, 67 are energised alternatively, to provide illumination either of the one colour or of the other. 7

The manner in which either lamp holder unit 589 or St) is fitted to the cellular grid 5 is' also shown inFIG. 4. The parts 53A and 53B of the spring 53 and similar parts of the springs 51B, 52A and 52B, make contact with the partition walls 7 only in the immediate vicinity of the screen 3.

The springs are shaped so that the limbs are compressed together by an amount to ensure that the friction between the ends of the springs and the partition walls may be relied upon to hold the unit 5%} inposition. The lengths of the limbs of the springs are such that the wires lie close to the back edges of the walls of the grid. The retaining parts are preferably held in position on the wires, to maintain a desired spacing between the retaining parts, by fiattening the wires slightly at positions 61, 61A and 62, 62A near to the coupling pieces 51 and 52 respectively.

As already stated, lamp holders may be used with the retaining parts in compartments separated by one or more compartments. Because of this feature, the back of the display panel may be left unobstructed in certain compartments, apart from the grommets and sockets and the wires between the retaining parts. Furthermore, the retaining parts may be spaced so that one or more partition Walls of the compartments separating the retaining parts may be removed. This greatly facilitates the provision of other structural members and the provision of linkages for driving any moving parts which may be mounted on the front of the display panel.

FIG. 4 also illustrates the manner in which the electric lamps are mounted in the unit. The grommet 55 is mounted between wires 54 and 54A, so that the wires lie in groove of the grommet 55.

The width of the boss of either the round or the square grommet is substantially equal to the distance between adjacent wires. The width of the groove 60 is slightly less than the wire diameter, so that the wires are gripped by the grommet flanges and the grommet is held in the desired position; The lamp socket 56 is inserted in the centre hole of the grommet so that the lamp 57, retained in the socket 56, is positioned with the lamp bulb in cell 9". The diameter of the hole is such that the grommet is expanded by an amount suflicient to retain the socket in place.

The lamp 67 is located in identical fashion between its supply. wires 54B and 54C.

Since the grommet 55 must be of insulating material if the supply wires are bare, it will be readily understood that lamps are not necessarily supported by their own supply wires. The connections 58, 58A may be made where necessary.

In the examples shown in the accompanying drawings, the compartments 9 and 9' are included in vertical and horizontal rows of compartments respectively. The compartments are square as viewed from the rear of the grid 5.- It is therefore possible to arrange the retaining parts in such a manner that the springs of the retaining parts engage either vertical or horizontal walls of compartments. For example, in FIG. 1, the lamp holder of FIG. 3 can be fitted with the retaining parts in compartments 9 so that the wires 54 to 54C run vertically, or in compartments 9 so that the wires run horizontally. This can be of importance when it is desired to accommodate moving parts inside certain of the compartments and it is of advantage in permitting removal of either vertical or horizontal partition walls from these compartments.

What I claim is:

l. .A back-lighted display panel comprising a translucent screen, at least one cellular grid member including partition walls extending from a front face to a rear face of the grid member and bounding open-ended cells, the grid memberbeing bonded to the rear face of the screen along the forward edges of the partition walls, at least one elec tric lamp, at least one electric lamp holder unit, each lamp holder unit including at least two retaining parts, each retaining part being located in one of the cells of the grid member, saidretaining parts being comprised of spring members of generally Y-shape having arms engaging said partition walls to retain the lamp holder unit in place in relation to at least two cells in a row of cells of the grid member, and an intermediate part engaging a coupling piece, each said coupling piece being engaged by and spacing apart a plurality of said spring members and carrying a plurality of supply wires for connecting said electric lamp to a source of electricity, and said electric lamp,

5 being carried in a holder supported by a pair of said supply wires.

2. A back-lighted display panel as claimed in claim 1, in which said spring members have a folded part intermediate the said arms, said folded part being dimensioned to receive said coupling piece and having a detent to hold the said coupling piece in the engaged position said coupling piece being strip-like.

3. A back-lighted display panel as claimed in claim 1, in which parts at least of the display panel are provided with a plurality of lamps of different colour to provide back-lighting of alternative colour.

References Cited by the Examiner UNITED STATES PATENTS Luhrnan 40-132 Wolf 240-10 Ross 240-52.1 X Appleby 240-10 Zador 240-52 Johnson 240-90 Spinetta 240-9 Blitzer 240-78 Koch 40-132 NORTON ANSHER, Primary Examiner. 

1. A BACK-LIGHTED DISPLAY PANEL COMPRISING A TRANSLUCENT SCREEN, AT LEAST ONE CELLULAR GRID MEMBER INCLUDING PARTITION WALLS EXTENDING FROM A FRONT FACE TO A REAR FACE OF THE GRID MEMBER AND BOUNDING OPEN-ENDED CELLS, THE GRID MEMBER BEING BONDED TO THE REAR FACE OF THE SCREEN ALONG THE FORWARD EDGES OF THE PARTITION WALLS, AT LEAST ONE ELECTRIC LAMP, AST LEAST ONE ELECTRIC LAMP HOLDER UNIT, EACH LAMP HOLDER UNIT INCLUDING AT LEAST TWO RETAINING PARTS, EACH RETAINING PART BEING LOCATED IN ONE OF THE CELLS OF THE GRID MEMBER, SAID RETAINING PARTS BEING COMPRISED OF SPRING MEMBERS OF GENERALLY Y-SHAPE HAVING ARMS ENGAGING SAID PARTITION WALLS TO RETAIN THE LAMP HOLDER UNIT IN PLACE IN RELATION TO AT LEAST TWO CELLS IN A ROW OF CELLS OF THE GRID MEMBER, AND AN INTERMEDIATE PART ENGAGING A COUPLING PIECE, EACH SAID COUPLING PIECE BEING ENGAGED BY AND SPACING APART A PLURALITY OF SAID SPRING MEMBERS AND CARRYING A PLURALITY OF SUPPLY WIRES FOR CONNECTING SAID ELECTRIC LAMP TO A SOURCE OF ELECTRICITY, AND SAID ELECTRIC LAMP BEING CARRIED IN A HOLDER SUPPORTED BY A PAIR OF SAID SUPPLY WIRES. 